The app is free to use, and by “free” I mean it doesn’t cost you any money, but you will be paying with your privacy. Much like Facebook and Google products, you’re trading your private meta data in exchange for using a service for free. It’s not clearly stated on Tezlab’s website, but I have no doubt that they are making money by data mining the anonymized data of their users, and then selling access to that data to third parties. If that’s not how they’re making their money, then they don’t have a business. It’s a personal preference and choice if you’re comfortable with that exchange.
Apps For Tesla Owners - Tezlab vs. TeslaFi